Technical Abstract:
Research conducted at the Catfish Genetics Research Unit, USDA-ARS, comparing growth, fillet yield, and disease resistance of channel catfish, blue catfish and their hybrids is reviewed. Growth to market weight (>454 g) in ponds was compared in four channel catfish strains and hybrids among females from each channel strain and blue catfish males. Relative to their corresponding purebred channel catfish strains, growth was superior for two hybrids, similar for one hybrid, and slower for one hybrid. Fingerlings from a fifth channel catfish strain grew faster than blue catfish and their reciprocal hybrids in aquaria regardless of dietary protein level. None of the hybrids tested have grown as fast as our fastest growing channel catfish strain. A channel female x blue male hybrid had higher fillet yield (48.4%) than its parental blue (46.2%) and channel catfish (44.7%) strains. After exposure to Edwardsiella ictaluri, mortality was highest for a relatively susceptible channel catfish strain, lowest for a blue catfish strain, and intermediate for their channel female x blue male hybrid. Mortality was not different among genotypes in two ESC challenges involving a blue catfish strain, a resistant channel catfish strain, and their reciprocal hybrids. Resistance to proliferative gill disease was determined for a channel catfish strain, a blue catfish strain, and their channel female x blue male hybrid stocked into a pond experiencing PGD losses. Gill damage was severe and mortality was 100% for channels and hybrids, but gill damage was slight and mortalities low (24%) for blues. Although some hybrids may be superior to some channel catfish strains for certain traits, not all hybrids are superior to the best channel catfish strains for all important traits.